A Texas hospital here has acknowledged an error occurred in its pharmacy that caused the death of two newborn twins.

Although the hospital says doctors found no direct links to the overdose, as many as 17 babies were given overdoses of the blood thinner Heparin at the neonatal intensive care unit of Christus Spohn Hospital South on July 4.

According to the hospital, pharmacy workers made a "mixing error" and the heparin that was given was 100 times stronger than recommended. Small doses of heparin, an anticoagulant, are routinely used to clean, and prevent blood from clotting in, patient's IV lines.

In a news conference on Friday, the grandmother of the children who died demanded answers from the hospital and said the family was devastated. The children were scheduled to be buried on Saturday, the same day family had planned to host a baby shower.

Though the investigation continues, the two pharmacy workers involved have reportedly gone on voluntary leave. The dead babies' parents obtained a court order preventing the hospital from destroying any records related to the overdose.

Nurses came to know about the heparin error on July 6 and immediately controlled the situation by proper medication. Local media reported that a third couple has hired an attorney after their child was also accidentally given an overdose of Heparin. That child is currently on a ventilator.

In 2006, actor Dennis Quaid sued a heparin maker after his children's overdose was traced to a hospital pharmacy worker who misread the labels. Luckily his twins were saved. The actor is urging lawmakers to hold pharmaceutical companies responsible and to require a barcode medication system for hospitals.

In September 2006, heparin received worldwide publicity when three prematurely-born infants died after they were mistakenly given overdoses of heparin at an Indianapolis hospital. According to various studies, one in every 15 children in hospitals is the victim of an accidental overdose, serious drug reaction, or medicine mix-up.